Astron has an Over-Voltage protection option that is an add-on accessory. In the past it was an option or included on some models. If the regulation series transistor shorts or the regulation circuits malfunctions, then the over-voltage protection shorts the output and blows the fuse(s).
My present RS-35M included it in the purchase. Since the late 70s or early 80s, I have used various current rated Astrons in both 12 and 24 volts with few if any issues except when Florida Flash & Flicker passed an EMP or such down the line! BTW - Never have heard it and it is well over 10 years old. George AI4VZ -----Original Message----- From: Charlie T Sent: Monday, June 10, 2019 7:57 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Silent power supply for a K3s Any supply that is regulated, whether a switching or linear regulator circuit is used, has the potential to "take-out" the radio because if the regulating circuit fails, the un-regulated voltage which is normally significantly higher than the regulated voltage will be applied to the radio. In a 12 - 14 V supply, this could very well damage anything it is connected to, from a simple 12V light bulb to your fancy new SS radio. That said, many good quality commercial power supplies have what is called a "crow-bar" circuit which is essentially a big SCR across the supply's output, with its gate driven by a voltage sensing circuit set a level slightly higher than the supply's normal output, say 16V. The action is if the regulator fails, the sensing circuit fires the SCR, which is hopefully big enough to effectively short the power supply's output and ether trigger a fold-back current limiting * circuit, or blow a fuse. 73, Charlie k3ICH *Unfortunately, in many supplies, the current limiter AND voltage regulator use the same active device, so in a fault situation, blowing the fuse is the last resort to a safe shut down. -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Bert Sent: Monday, June 10, 2019 12:16 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Silent power supply for a K3s How would a switched PS take out a radio? Bert VE3NR On 6/9/2019 11:40 PM, Jim - N4ST wrote: > I don't know how common it is, but eHam lists several failures of the > MFJ-4230MV supply that took out the rig attached to it. > Looking at the reviews they are pretty much a 5 (love it) or a 0 (it > smoked my rig when it failed). > > ________ > 73, > Jim - N4ST > > > -----Original Message----- > From: elecraft-boun...@mailman.qth.net > <elecraft-boun...@mailman.qth.net> On Behalf Of Richard Zalewski > Sent: Sunday, June 9, 2019 19:53 > To: Leroy Buller <lee.bul...@gmail.com> > Cc: Elecraft Reflector <elecraft@mailman.qth.net> > Subject: Re: [Elecraft] Silent power supply for a K3s > > I did two of the Samlex and returned them both. The fan problem drove > me crazy. I replaced it with a MFJ-4230MV and love it. Quiet cool > and good metering. > > Richard > *W7ZR* ex:5C5Z, CN2ZR, K2JSP, W6SBZ, W7KXR, K9ZIJ, W9KNF, W0KDF, > W0MQU, J68ZR, KC6ZR, PJ4/W7ZR, KH2,W7ZR, KH6/W7ZR, V31ZR, VK4AAZ, > XE2DV > > > *Be joyful in hope, patient in affliction, faithful in prayer* > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net Please help support this email > list: http://www.qsl.net/donate.html Message delivered to > ve...@bell.net ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to pin...@erols.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to gdanne...@gmail.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
